Ignition device for aircraft engines



March 14, 1933. E. K LA|BER 1,901,

IGNITION DEVICE FOR AIRCRAFT ENGINES Original Filed July 13, 1931 refitted Mar. 14, 1933 UNITED STATES PATENT OFFICE EBICH manna, or srum'ennr, GERMANY, nssren'on mo nonuni- BOSCH .AKTIEN- GESELLSOHAFT or s'rurman'r, GERMANY IGNITION DEVICE FOR AIRCRAFT ENGINES Application filed July 18, I931, Serial No. 560,585, and in Germany October 7, 1980.. Renewed July 19,1982. z '3 The present invention relates to a battery ignition device more particularly for aircraft engines.

The objectof the invention is to obtain satisfactory ignition under all working conditions by using devices which are to be kept as simple as possible and eliminate sensitive constructions which can be the causes of unsatisfactory working.

As is known, with aircraft there are only two definite working conditions, idle running and running on full load. As a rule, therefore there are two adjustments of the ignition device, these being a predetermined advanced ignition position and a predetermined retarded ignition position. It is known to combine two make and break devices with these two' adjustments one being permanently adjusted to advanced ignition and the other permanently adjusted to retarded ignition, these being connected into the primary circuit as required.

On the other hand, with full load, large spark gaps are as is known used for aircraft engines. In order to obtain this, it is known to vary the resistance connected into the circuit in front of the ignition coil, automatically by governors working in dependence upon the speed of rotation, as well as to alter the closed or condenser charging period by using two make and break devices which are connected in parallel and can be mutually adjusted by a certain amount. These regu Figure 2 in which the induction of the ignn lating or governing devicesharbour a source of trouble in themselves because they are very dependent upon the lubrication, hearing and property of contacts of the governor and the lik On the basis of the knowledge that there is no need for any regulating steps ordegrees betweenidle running and loaded running, these disadvantages can be eliminated according to the invention with aircraft battery ignition in that mechanisms are providedwhich influence the capacity of the sparks in such a way that they are not harmfully large at the retarded ignition position but are adequate at the advanced ignition position.

In one form of construction a constant remake and break devices themselves as rew.

sistances. In addition the closed or make period of the advanced ignition make and break device can be made permanently greater than that of the retarded i ition make and break device in order to elp the two different resistances in their endeavour to obtain a strong spark at high speed of rotation. In addition to the procedure already mentioned, the known change in induction of the coil can be utilized, the operation of which is preferably positively combined with the reversal. of retarded to advanced ignition. Various forms of construction of the invention are shown in the drawing in which Figure-1 shows a battery ignition device with advanced and retardedignition make and break devices in each circuit of which a special resistance is inserted.

Figure 2 shows a battery ignition device having two .make and break devices and a separate cam for each make and break device, the closed or make period of which is made relatively different.

Figure 3 shows the same arrangement as tion coil can be varied in addition.

In Figure 1 one end of the low tension windin 1 of the ignition coil is connected to one p0 e of the battery 3, the other pole of which is earthed. One end of the high tension coil 2 is also earthed, whilst the othe'ris.

led through the distributor 4 to the sparking plugs 5. The end of the coil 1 which is not connected to the battery is connected to the pivotal-point 6 of a switch arm of the switch A which can contact with any of the-three, contacts 7 8 and-9. Of these, 7 is an idle contact and 8 is connected to the insulated make sistance 10. lhis ignition coil has two make and break devices having the insula ed arms 12 and 13, and the corresponding stationary contacts 14, 15 which are earthed. The make and break device arms 12 and 13 are moved by the rotating-cam 14 which is driven in timed relation by the engine. The arm 13 is connected to the contact 9 of the switch A through the intermediary of a resistance 11. The essential feature of the connection is that the resistances are constant and that the resistance 10 lying in the advanced ignition circuit is smaller than the resistance 11 lying in the retarded ignition circuit.

' The wiring and arrangement according to- Figure 2 is the same as in Figure 1 with the exception of the make and break device.

In order to obtain' difierent breaking or.

interruption periods for the advanced ignition make and break and the retarded ignition make and break a separate rotating cam is provided for each make and break circuit. The arm 12 is operated by the cam 17 and the make and break device arm 13 is operated by the cam 18. The two cams are mounted on the same shaft and are so mutually displaced that when the cam shaft rotates in clockwise direction, first the arm 12 is raised and then the arm 13 is raised actually so much later as the angle line a a pursues the angle line a a In addition the two cams are constructed differently. Difierent breaking or interruption times correspond to the angle 1 and 2 at the same velocity of rotation. As long as the cam follower 19 of the arm 12 is within range of the angle 0& which in the example shown occurs four times in one revolution of the cam and the cam follower 20 ofthe arm 13 is within range of the angle 0:

- the arms are lifted, that is to say the corresponding circuits are broken. As the angle a of theretarded ignition make and break device is greater than the angle a of the advanced ignition make and break device the making or closed period of the advanced ignition make and break device is also greater than that of the retarded ignition make and break device. This different form of con-. struction of the make and break device increases the action which it is endeavoured to obtain through the series resistance.

In Figure 3 the low tensioncoil 1 is tapped at a place 25 so that the induction of-the coil may be changed. :The end of the coil 1 is led to the contact 24 of'the switch Binstead of directly to the terminal'8 and the tapping at 25 arm of the switch A. The pivotal point 21 is connected to the pivotal point 6 of the contact arm of the switch A;'the remainder of ,theconnection is .as shown in the wiring diagram oiFiguref2;

If in Figure 1 the contact arm of the switch A is connected to the contact 9 the current passes'from the battery through the'coil 1, the switch A and the series resistance 11 to the retarded ignitionmake and break device 13, 13;

The series resistance is chosen of such magmtude that the coil 1 and the make and break device contact place 15 are not overstrained. For advanced ignition it is reversed from contact 9 to contact 8: the current now passes through the series resistance 11 which is smaller than the resistance 10 so that a spark, which is capable of ignition, is even formed at high velocity.

The arrangement in Figure 2 only difiers from the arrangement in Figure 1 in that the retarded ignition make and break device has a shorter closed or making period than the advanced make and break device.

If the switch A is connected to the contact 9, that is to say, to retarded ignition, the resistance 11 and also a comparatively short closing or making period of the make and break device 13 prevent the coil 1 and the make and break contacts being too heavily loaded and more particularly the battery 3 being discharged to an unnecessarily high degree, even when the motor is running at a low speed of rotation. On the other hand with the connection to advanced ignition a good spark is produced by the resistance 10 which is small compared with the resistance 11, and a comparatively long making or closing period of the make and break device 12 even at a high speed of rotation.

In the arrangement shown in Figure 3 the induction of the coil 1 is changed in addition and actually in dependence upon the adjustment of the ignition timing. On that ac rest on the contact 24. The current accordingly passes through the entire coil 1 through the switch B, the switch A and the resistance 11 to the make and break device. The electrical and magnetic conditions are the same as in the arrangement of Figure 2. With the advanced ignition position of the switch A on the contact 8, the switch 13 is at rest on the contact 23. The current now only passes through one portion/of the coil 1 and then through the switches B and A and through the resistance 10 to the make and break device 12. The magnetic time constant of the coil has become smaller through the reduction in the number of windings and as a result the increase in current greater at a given voltage which'is very desirable in view of the, actual short making or closing periods at high speeds of rotation.

For starting the aircraft motora buzzer ignition is connected in known manner to the .pole of the switch.

retarded ignition make and break device viously used are eliminated as devices which are liable to become worn out, which are sources of failure and which require attention. A further advantage is the cheapening of the ignitiondevice and the reduction in Wei ht thereof which'is verydesirable in air-. cra t where a reserve ignition system is provided for each engine.

I declare, that what Iclaim is:

1. An ignition device for aircraft engines comprising a battery, an induction coil connected to said battery, a make and break ,device set in the retarded ignition position, a second make and break device set in the advanced ignition position, a' change-over switch, connected to said i nition coil, a resistance connected in series tween said first make and break device and one pole of the switch and a second resistance of less ohmic resistance connected in series between said second make and break device and the other 2. An ignition device for aircraft engines comprising a battery, an induction coil connected to said battery, a cam, an interrupter.

contact set in the advanced ignition position in relation to said cam and'operated thereby, a second interrupter contact, a second interrupter cam set in the retarded ignition posi tion with relation to said cam, a change-over switch connected to said induction coil and having a pair of contacts, a resistance connected in series between one of said switch contacts and the first interrupter contact and .a second resistance of greater ohmic resistance than the first resistance connected 1n.

having a shorter low portion than the firstcam, a second interrupter contact set in the retarded ignition position and operated by said second cam and a change-over switch connected to sa1d induction coil and having a pair of contacts, a resistance connected in series between one of said switch contacts and the first lnterrupter contact and a second resistance of greater ohmic resistance than the first resistance connected in series between the other switch contact and the second interrupter contact.

4. An ignition device for aircraft engines comprising a battery, an induction coil connected to said battery and having a tapping thereon, a cam, an interrupter contact op-v erated by said cam and set in the advanced ignition position, a second cam having a shorter low portion than the firstcam, a second interrupter contact set in the retarded ignition position and operated by said second cam, a resistance in series with the first interrupter contact, a resistance of greater ohmic resistance in serles with sa1d second I interrupter contact and means to alternaand break device set in the retarded ignition osition, a second make and break device set 1n theadvanced ignition position, and switch means for connecting either of saidmake and break devices in said circuit, the resistance ofthe circuit through said first mentioned make and, break device being greater than that through the second make andbreak device.

.6. An ignition device for internal combustion engines comprising a circuit including a source of current, an induction coil, a' make and break device set in the retarded ignition position, a second make and break device set in the advanced ignition position, and

switch means for connecting either of said make and break devices in said circuit,-the closed period of the make and break device set in the advanced ignition position being greater than that of the other make and break device.

' 7. An ignition device for internal combustion engines comprising a circuit including a "source of current, an inductlon coil, a make and break device set in the retarded ignition position, a second make and break device set in the advanced ignition position, and switch means for connecting either of said make and break devices in said circuit,- the resistance of the circuit through saidfirst-mentioned make and break device being greater than that through the second make and break device and the closed period of the second make and break device being greater than that of the first make and break device.

8. An ignition device for internal combus- "tion engines comprising 'a circuit including a source of current, an induction coil, a make and break device set in the retarded ignition position, a second make and break device set in the advanced ignition position, switch means for connecting either of said make and break devices in said circuit, and means for short circuitinga portion of the primary of said induction coil when the second make and break device is connected in circuit.

9. ignition device for internal combustion engines comprising a circuit including a source of current, an induction coil, a make and break device set in the retarded ignition position, a secondmake and break device set in the advanced ignition position, switch means for connecting either of said make and break devices in said circuit, the resistance of the circuit through-said first mentioned make and break device being greater than that through the second make and break device, and means for short circuiting a portion of the primary of said induction coil when'the second make and break device is connected in circuit.-

10. An ignition device forlqmternal combustion engines comprising a circuit including a source of current, an induction coil, a

- make and break device set in the retarded connected in circuit.

ignition position, a second make and break device set in the advanced ignition position, switch means for connecting either of said make and break devices in said circuit, the resistance of the circuit-through said first mentioned make and' break device being greater than that throu h the second make eriod of and break device and't e closed the second make and break -dev1ce being greater than that of the first make and break device, and mea'ns for short circuiting a portion of theprimary of said induction coil when the second make and break device "is 11. An ignition device especially for aircraft engines comprising a source of cur-- rent, an mductlon coll connected to said source, a make and break device set "in the retarded i ition position, a second make and break evice set in' the advanced ignition position, and means, including switch means to connect said make and break devices with said induction coil, to vary the primary current of said induction coil so that at retarded ignition gosition the current is not harmfully large an at advanced ignition sition it is large enough to produce a cient ark.

-In testimony whereof I hereunto a ed,

my signature.

ERICH KLAIBER. 

